BTC HashCard — Engineering Deep Dive Report
Date: March 25, 2026 Conducted by: Nikos Device: BTC HashCard (9x BM1370, ESP32-S3) Stock Firmware: magic-miner V1.0.0 (ESP-IDF v5.5.1, compiled Dec 29, 2025) Test Firmware: TNA V4.4 (ESP-IDF v5.3.4, custom HashCard board support) Device Codename: Supra (board version 403)
Disclosure
The @JingleMinershop approached the author and requested an independent engineering review of their HashCard product. One unit was provided free of charge with no strings attached, specifically for the purpose of a thorough hardware teardown, firmware analysis, and honest assessment. The vendor understood and accepted that the findings — both positive and negative — would be published in full. They raised no objections to any aspect of this report.
Executive Summary
The BTC HashCard is a well-engineered 9-chip Bitcoin mining device built around the BM1370 ASIC platform. Its hardware design demonstrates thoughtful engineering — dual stacked TPS546D24A voltage regulators, 3S3P ASIC topology for efficient voltage delivery, W5500 wired Ethernet, SPI LCD display, and a compact form factor with integrated heatsink.
The stock magic-miner firmware, while functional, raises significant privacy concerns due to undisclosed telemetry reporting to manufacturer-controlled servers. This report documents the complete hardware architecture, firmware analysis, and the process of bringing up Tech Nerd Army custom firmware V4.4 on the platform.
All findings are based on hands-on testing with a device owned by the investigator, serial log capture, NVS extraction, firmware binary string analysis, and TPS546D24A datasheet reference.
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Full report available here
https://github.com/CryptoIceMLH/HashCard
